title: Nonalcoholic fatty liver disease: intravoxel incoherent motion diffusion-weighted MR imaging-an experimental study in a rabbit model.
abstract: OBJECTIVE
  To evaluate the feasibility of using intravoxel incoherent motion (IVIM) diffusion-weighted imaging with multiple b values for the noninvasive diagnosis of nonalcoholic fatty liver disease (NAFLD).
  
  
  METHODS
  This study was approved by the institutional animal care and use committee. Twenty-seven 8-week-old rabbits were fed a variety of diets (from a standard diet to a high-fat, high-cholesterol diet) before IVIM diffusion-weighted imaging was performed with seven b values by using a 3-T magnetic resonance (MR) imaging unit. At histologic analysis of the animals, livers were categorized by NAFLD severity as normal, NAFLD, borderline nonalcoholic steatohepatitis (NASH), or NASH. The apparent diffusion coefficient and IVIM-derived parameters including true diffusion coefficient, pseudodiffusion coefficient, and perfusion fraction of the liver parenchyma were measured. Each parameter was correlated with NAFLD severity, and optimal cutoff values were determined by means of receiver operating characteristics analysis.
  
  
  RESULTS
  Perfusion fraction was significantly lower in rabbits with NAFLD than in those with a normal liver, and it decreased further as severity of NAFLD increased, with medians of 22.2%, 14.8%, 11.3%, and 9.5% in the rabbits in the normal, NAFLD, borderline, and NASH groups, respectively (ρ = -0.83, P < .001). Apparent diffusion coefficient, true diffusion coefficient, and pseudodiffusion coefficient were not significantly different between the NAFLD severity groups. In terms of the diagnostic performance of perfusion fraction, area under the curve values were 0.984 (normal vs NAFLD or more severe disease), 0.959 (NAFLD or less severe vs borderline or more severe disease), and 0.903 (borderline or less severe vs NASH) with optimal cutoff values of 15.2%, 13.2%, and 11.0%, respectively.
  
  
  CONCLUSIONS
  Perfusion fractions extracted from IVIM diffusion-weighted imaging may help in the differentiation of early stage NASH from simple steatosis.
authors.affiliation: From the Department of Radiology (I.J., J.M.L., J.H.Y., J.K.H., B.I.C.), Institute of Radiation Medicine (J.M.L., J.K.H., B.I.C.), and Department of Pathology (J.J.J.), Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Korea.
authors.forename: Ijin
authors.initials: I
authors.lastname: Joo
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Lee
authors.forename: Jeong Hee
authors.initials: JH
authors.lastname: Yoon
authors.forename: Ja Jun
authors.initials: JJ
authors.lastname: Jang
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
authors.forename: Byung Ihn
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005234:Fatty Liver / Q000473:pathology*; D005240:Feasibility Studies; D007091:Image Processing, Computer-Assisted; D008111:Liver Function Tests; D008297:Male; D065626:Non-alcoholic Fatty Liver Disease; D011237:Predictive Value of Tests; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index